Ryan was responding to a comment by Vice President Joe Biden, who said Tuesday that the Romney-Ryan tax plan would lead to higher taxes on middle-class families that have "been buried the last four years."
Ryan and Romney quickly made it known that they agreed with Biden, and argued the past four years under President Barack Obama have been bad for the middle class. They said a change in the White House was the solution.
"We agree," Ryan said. "That means we need to stop digging by electing Mitt Romney the next president of the United States.
"Of course the middle class has been buried," he continued. "Buried by regulations, buried by taxes, buried by borrowing. They're being buried by the Obama administration's economic failures."
During a campaign appearance in Charlotte, N.C., Biden told about 1,000 people that Romney would cut taxes for millionaires at the expense of the middle class.
"This is deadly earnest. How they can justify raising taxes on a middle class that has been buried the last four years?" Biden asked. "How in Lord's name can they justify raising their taxes with these tax cuts?"
Lis Smith, a spokeswoman for Obama's re-election campaign, said the Republican response to Biden was "another desperate and out-of-context attack."
Smith said Biden has long said, as he did Tuesday, "that the middle class was punished by the failed Bush policies that crashed our economy."
A vote for Romney and Ryan "is a return to those failed policies," she said.
At a rally earlier Tuesday outside the county courthouse in Clinton, Iowa, Ryan said the GOP ticket would help more people find jobs so they can pay taxes. He was responding to someone who asked why so many people don't pay federal income taxes. The question apparently was prompted by the recent release of secretly recorded videotape of Romney telling deep-pocketed donors he would never win the votes of the 47 percent of Americans who don't pay federal income taxes.
Obama and other Democrats have criticized Romney for the remarks.
"We have 47 percent of the people in the United States pay no taxes, federal income taxes," the voter told Ryan. "Is there any way possible that this 47 percent can pay a nominal fee or something so that they feel that they have small ownership of the government and maybe they don't take all the handouts?"
Ryan said the answer is more jobs.
"I have an idea. Let's help them get jobs so they can get good paychecks and then they're good taxpayers," Ryan said, ignoring the fact that military members serving in war zones and seniors are among the millions who do not owe federal income taxes.
Ryan acknowledged, however, that Romney's comments about the 47 percent muddled the political landscape.
"Sometimes the point doesn't get made the right way," Ryan said, but stood by the Romney campaign's position that the economy under Obama has been lousy and that a GOP White House would fare better for workers.
Romney's campaign has suffered from the release of the hidden-camera video of Romney saying 47 percent of Americans see themselves as victims and depend on government help.
Last year, 46 percent of U.S. households paid no federal income tax, according to a study by the nonpartisan Tax Policy Center. Most do pay other federal taxes, including for Medicare and Social Security, as well as other levies, such as sales taxes.
Associated Press writer Philip Elliott in Clinton, Iowa, contributed to this report.